BIOL 152 1st Edition Lecture 14 Outline of Last Lecture I Plants respond to light a Discovery of plant hormones i Auxin first one discovered 1 Named by Fritz Went 2 Produced by stem tip 3 Influences plant growth II Other plant hormones a Cytokinin i Stimulates cell division b Gibberellin i Stimulates germination ii Promotes fruit growth c Abscisic Acid i Induces dormancy d Ethylene i Causes senescence ripening III Other tropisms a Gravitropism b Thigmotropism Plant Defense Outline I II III Advantages and disadvantages of a plant s defenses Pathogens a Mode of entry b Types of pathogens Plant immune responses basal and specific a Hypersensitive response b Acquired resistance Outline of Current Lecture I Diversity of land pants a Non vascular land plants Bryophytes i Gametophytes dominant ii Liverworts 1 Microscopic sporophyte These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute II iii Mosses 1 Macroscopic sporophyte 2 Sphagnum moss iv Hornworts 1 Photosynthetic sporophyte Spore producing vascular plants a Lycophytes first vascular plants i Extinct ancestors trees ii Extant species understory herbs iii Leaves with single vascular trace b Ferns i Multiveined leaves ii Diverse growth forms and habitats c Seed producing vascular plants i Gymnosperms 1 Naked seeds 2 Junipers 3 Redwoods 4 Ginkgos 5 Cycads ii Angiosperms 1 Fruits cover seeds 2 Highly diverse 3 Co evolution with pollinators Current Lecture What two hormones are most likely responsible for the change in plant morphology and why Auxin and cytokinin both responsible for growth factors of plant whether increasing or decreasing Types of defenses Mechanical Chemical Ecological Mechanical Structure based defense Thorns Spines Chemical Plants can release chemicals to repel predators What can trigger a chemical defense Physical damage Can respond to sounds vibrations in the environment Detecting of attacker compounds Ecological Ex Symbiosis of ants and acacia The plants house and feed the ants The ants protect the plant by attacking any foreign predators What about the pollinators How will they get to the plant if the ants attack them every time The plants produce a chemical to repel the ants during pollination periods Adaptation in grasses fig 32 14 They have low apical meristems allowing them to be mowed grazed without dying Resources and defense 32 15 Constitutive vs inducible defenses Diversity of land plants NONVASCULAR Liverworts 33 3 b Moss Obvious sporophyte o Sphagnum moss 33 5 Can reduce pH in water of it habitat Hornworts Macroscopic sporophytes o Persistently photosynthetic Why are mosses more diverse More physiological adaptions to stress than others VASCULAR PLANTS Lycophytes Oldest Xylem and phloem Left fossils Single veined leaves Ferns Multiveined leaves Starts as croziers Large leaves Can thrive in many different environments Epiphytes capable of living on other plants Diversity of gymnosperms Naked seeds no fruit covering Embryo already inside o Surrounded by gametophyte food Seed embryo sporophyte packed with a lot of nutrients and covered by a seed coat Ex o o o o Junipers common shrubs Redwoods Gingkos extinct in nature Cycads house plants Gymnosperms and Angiosperms SEEDS AND POLLEN Angiosperms Flowering plants Fruit covering for the seed o Greater protection and ability for dispersal All human food is from angiosperms Very large Origin unknown Co evolved with pollinators o Rapid diversification
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